1. Technical Field
The present disclosure relates to a rubber composition for use in tire treads and a pneumatic tire using the same, and particularly relates to a rubber composition for use in tire treads and a pneumatic tire using the same having high grip performance at initial traveling, wherein said performance is maintained for an extended period of time while traveling, even after heat builds up in the tread, and also having superior wear resistance.
2. Related Art
Conventionally, there has been a demand that racing tires have high grip performance from initial traveling and maintain high grip performance even after heat builds up in the tread. It is also important that this performance be balanced with wear resistance.
A technique for enhancing grip performance exists wherein a styrene-butadiene copolymer rubber (SBR) with a high glass transition temperature (Tg) is compounded. However, with this technique, there is a problem in that grip performance at initial traveling and wear resistance is sacrificed. Additionally, techniques also exist including compounding a large amount of carbon black having a small particle size or compounding a tackifying resin having a high softening point. However, while these techniques lead to enhancements in grip performance, there are problems in that grip performance is not maintained and wear resistance is inferior with the former technique and grip performance at initial traveling is sacrificed with the latter technique.
WO/2005/090463 describes a pneumatic tire using as a tread rubber a rubber composition comprising a rubber component containing 80 wt % or more of a natural rubber and/or an isoprene rubber and, per 100 parts by weight thereof, 20 parts by weight or more of an inorganic filler constituted by non-petroleum resources and 10 parts by weight or more of a resin having a softening point of 60° C. or higher. However, with the technique described in WO/2005/090463, the conventional problems remain and, specifically, it does not sufficiently maintain grip performance including that at initial traveling and wear resistance at a high level.